COMMON UNSOUNDNESSES AND VICES 179 



TUMORS 



Tumors are new growths which appear at times in various tissues 

 of the body from no apparent cause. They may be either benign 

 and slow in development or malignant and spread very rapidly. 

 Benign tumors remain localized and are not dangerous unless vital 

 organs are involved. Warts are benign tumors. They occur on 

 the thin parts of the skin. To remove warts pull or twist them off, 

 cut them away with a knife, or burn them with a hot iron. All 

 malignant tumors should be excised completely and early with the 

 surgeon's knife, in order to prevent them from encroaching upon 

 neighboring tissues and spreading to other parts of the body. As 

 a rule; caustic agents are to be employed to destroy tumors only on 

 expert advice, for they tend to cause them to spread and favor their 

 growth. 



A common form of malignant tumor, occurring in white and 

 gray horses, is known as melanosarcoma. It is always black in 

 color and contains a large amount of melanin, the pigment found 

 in the skin. 



CANCERS 



Cancers are malignant tumors composed of epithelial and 

 connective tissues. They have a tendency to persist and grow 

 down into the surrounding tissues. They are found either on the 

 surface epithelium or in the epithehal cells of glands. The causes 

 are various and numerous irritating agents. Recent experiments 

 go to show that cancers have an infectious origin and can be trans- 

 planted in animals of the same species. Cancers occur most fre- 

 quently on the head and penis of the horse. A diagnosis is made by 

 sectioning and staining pieces of the tissue, or by applying the 

 Abderhalden test to the blood-serum of the patient. Treatment 

 consists in complete and early excision whenever practicable. 



DEFECTIVE CONFORMATION 



Defects in conformation and malformations of various kinds 

 should be avoided in horses used for breeding purposes. Although 

 these may not be of a nature to be classed with the unsoundnesses, 

 they do reduce the value of the animal. Some are inherited, 

 others are acquired. 



Badly formed limbs reduce the efficiency to a greater extent 



